100 lines
3.3 KiB
Markdown
100 lines
3.3 KiB
Markdown
`pytest` is an essential Python library for developers focused on testing their code. It provides a powerful yet simple framework for writing and running tests, supporting unit tests, functional tests, and more complex test scenarios. `pytest` stands out for its ease of use, detailed assertions, fixtures for setup and teardown, and support for parameterized testing, among other features. Here's a concise reference guide for common use cases with `pytest`:
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# `pytest` Reference Guide
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## Installation
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```
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pip install pytest
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```
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## Basic Usage
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### Writing Your First Test
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Tests are Python functions that start with `test_`. Place your test functions in files named `test_*.py` or `*_test.py`.
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```python
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# content of test_sample.py
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def func(x):
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return x + 1
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def test_answer():
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assert func(3) == 4
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```
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### Running Tests
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Navigate to the directory containing your test file and run:
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```
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pytest
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```
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`pytest` will discover and run all tests following its naming conventions.
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## Assertions
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`pytest` uses standard Python `assert` for verifying expectations and values in tests, providing detailed output on assertion failures.
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```python
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def test_check_equal():
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assert func(4) == 5
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```
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## Fixtures
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Fixtures provide a powerful mechanism for setup and teardown operations, creating test data, and configuring the test environment.
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```python
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import pytest
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@pytest.fixture
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def input_value():
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return 38
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def test_divisible_by_2(input_value):
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assert input_value % 2 == 0
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```
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## Parameterized Tests
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Parameterize tests to run the same test function with different inputs.
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```python
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@pytest.mark.parametrize("test_input,expected", [(1, 2), (2, 3), (3, 4)])
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def test_eval(test_input, expected):
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assert func(test_input) == expected
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```
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## Handling Exceptions
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Test that a certain exception is raised using the `pytest.raises` context manager.
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```python
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def test_exception():
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with pytest.raises(ValueError):
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raise ValueError
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```
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## Skipping Tests
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Skip a test function or expect it to fail.
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```python
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@pytest.mark.skip(reason="not implemented yet")
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def test_to_skip():
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pass
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@pytest.mark.xfail
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def test_might_fail():
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pass
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```
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## Using Plugins and Integrations
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`pytest` supports numerous plugins for integration with other tools and extending its functionality, such as `pytest-django` for Django projects, `pytest-asyncio` for testing asyncio code, and many more.
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## Configuration
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Use a `pytest.ini`, `tox.ini`, or `pyproject.toml` file to configure `pytest` behavior, like custom markers, test paths, and plugin configurations.
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## Advanced Usage
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`pytest` offers a broad spectrum of advanced features, including but not limited to test fixtures scopes, using mocks, and integrating with continuous integration (CI) tools.
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## Continuous Integration
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`pytest` can easily integrate with CI tools like Jenkins, GitHub Actions, or GitLab CI, running your test suite on every push or pull request automatically.
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`pytest` simplifies and accelerates the testing process, encouraging best practices in test writing and execution. Its extensive documentation and active community make it a go-to choice for Python developers looking to ensure their code meets the highest standards of quality.
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`pytest` is favored in the Python community for its rich ecosystem, simplicity, and ability to handle not just simple unit tests but also complex functional testing for applications and libraries. |